Seal

ABSTRACT

A seal adapted to be fitted over the open end of the barrel of a hypodermic syringe comprises a cap of a non-latex elastomer having a central aperture which is sufficiently small as ordinarily to retain liquid therebehind but which can be deformably expanded to allow passage of the rearward end of a needle hub for engagement with the barrel.

[0001] This invention relates to the fitting of needle components to thebarrel of a hypodermic syringe.

[0002] It is common practice to fit a syringe with a filling needle forthe purpose of drawing liquid into the barrel of the syringe byretraction of its plunger from a vial often of the kind having a rubbercap which is penetrated by the filling needle. After the syringe hasbeen charged, the filling needle is removed and replaced by a needle tobe used for administration of an injection into a patient. Yet again itis often necessary to change a needle to meet patient requirements.

[0003] During the change of needle where the syringe is of a type havinga large open end to permit needle retraction, care must be taken toavoid spillage of the contents of the syringe through the open end ofthe barrel.

[0004] It is an object of the present invention to provide a seal forthe open end of a syringe barrel which overcomes the problem aforesaid.

[0005] According to the present invention there is provided a sealadapted to be fitted over the open end of the barrel of a hypodermicsyringe comprising a cap of a non-latex elastomer having a centralaperture which is sufficiently small as ordinarily to retain liquidtherebehind but which can be deformably expanded to allow passage of aneedle mounting portion for engagement with the barrel.

[0006] The cap may be of silicone rubber.

[0007] The aperture may be circular.

[0008] The aperture may take the form of a number of slits extendingradially outward from the centre of the cap.

[0009] The cap may comprise a circular disc having a cylindrical skirtextending from its rear face.

[0010] The internal periphery of the skirt may be provided with axiallyspaced circumferential ribs adapted to engage with circumferentialgrooves on the end of the barrel to hold the cap in position.

[0011] The invention also includes a syringe barrel fitted with a sealas aforesaid.

[0012] The syringe barrel may be used with both a filling needleassembly and an injection needle assembly in which case the cap isexpandable to allow fitting of both the filling needle and the injectionneedle to the barrel.

[0013] The arrangement may be such that the mounting portion of theinjection needle is engaged with the barrel through a one-way couplingmeans formed by interfitting components on the needle mounting portionand the barrel whereby the injection needle once assembled to the barrelcannot be disengaged from the barrel (at least not without damaging thecomponents). The filling needle may also be engageable with the barrelwith the aid of the one-way coupling means associated with the barrelbut in such a way that the filling needle may be subsequentlydisengaged.

[0014] The one way coupling means may comprise a threaded connection ora bayonent-type connection between a male part and a female part, onepart being associated with the barrel and the other part beingassociated with the barrel.

[0015] The one way coupling means may for example comprise a threadedconnection between a male and a female part, there being a void in anupstanding portion of the thread on each part and a barb in the void onone of the parts, the arrangement being such that when the parts arethreadedly engaged, resilient deformation of at least one of the partsenables the barb to latch behind an end of a thread at the void in theother of the parts to prevent subsequent disconnection of the parts.

[0016] Another aspect of the invention concerns a threaded connectionbetween a male part and a female part which, when properly threadedlyengaged, cannot be disconnected, particularly, though by no meansexclusively, suitable for joining components of fluid handling medicaldevices such as syringes, cannulas and catheters for example.

[0017] According to this aspect of the invention there is provided athreaded connection between a male and a female part, there being a voidin an upstanding portion of the thread on each part and a barb in thevoid on one of the parts, the arrangement being such that when the partsare threadedly engaged, resilient deformation of at least one of theparts enables the barb to latch behind an end of a thread at the void inthe other of the parts to prevent subsequent disconnection of the parts.

[0018] There may be on each part a two-start thread, the upstandingportion of each thread having a circumferential extent of less than 180°whereby there are voids between the ends of the two threads on each partand diametrically opposed barbs in the voids on the male part.

[0019] The height of each thread on the female part may increase fromone end to the other which provides the abutment against which a barblatches.

[0020] The invention will be further apparent from the followingdescription by way of example with reference to the figures of theaccompanying drawing, in which:

[0021]FIG. 1 is a perspective view of the resiliently-deformable sealingcap associated with the barrel of a hypodermic syringe;

[0022]FIG. 2 is a fragmentary perspective view of a syringe barrelfitted with the cap and about to receive a filling needle device;

[0023]FIG. 3 is a view similar to that of FIG. 2 but wherein the barrelis about to receive the hub of an injection needle;

[0024]FIG. 4 is a perspective view of the forward end of a syringebarrel on an enlarged scale and with the resilient cap omitted; and

[0025]FIG. 5 is a perspective view on an enlarged scale of a connectorarrangement for permanently coupling the injection needle to the syringebarrel.

[0026] Referring firstly to FIG. 1, it will be seen that the seal,generally indicated at 10, comprises a cap having a circular discportion 11 and a cylindrical skirt 12 extending from the rear face ofthe disc portion 11. A circular aperture 13 is provided through thecentre of the disc portion 11. The seal 10 is a moulding of siliconerubber.

[0027] The inner periphery of the skirt 12 is provided with axiallyspaced circumferential ribs (not shown) which engage circumferentialgrooves on the forward end part of a syringe barrel 14 to enable the capto fit securely over the open end of the barrel.

[0028] The aperture 13 is sufficiently small as to retain liquidtherebehind having regard to the surface tension of the liquid even ifthe barrel 14 is pointed downwardly without deliberate violent movementsuch as shaking.

[0029] The aperture 13 may be resiliently expanded to permit entry ofthe mounting portion 15 of a filling needle assembly 16 whose needle 17is protected until required by use by a frangible guard 18 (see FIG. 2).The rearward end 15 has a screw thread 19 which engages a complimentarythread (not shown) within the barrel 14 such that a raised sealing lip23 of the seal is compressed between the mounting portion 15 and barrel14 to form a tight seal.

[0030] After the barrel has been filled by insertion of the needle 17into a vial of liquid which is drawn into the barrel 14 by retraction ofthe syringe plunger (not shown) the filling needle device 16 isdisengaged and discarded and an injection needle 21 is fitted to thebarrel. The hub or mounting portion 20 of the injection needle 21 alsohas a screw thread 22 which engages the thread within the barrel 14again compressing the cap between the parts to form a seal.

[0031] During the needle change, i.e. during the interval betweendetachment of the filling needle device and fitting of the injectionneedle, the aperture 13 relaxes to its original size preventingaccidental spillage of liquid from the barrel 14.

[0032] Referring now to FIGS. 4 and 5, a one way coupling means in theform of a threaded connection is illustrated. The coupling comprises athreaded female socket part 112 at the forward end of the barrel 14adapted to receive a threaded male part 113 of a mouting portion 110 ofthe needle assembly. Each of the parts 112 and 113 is provided with atwo-start right handed thread. The upstanding portion 114 of each of thefour threads has a circumferential extent of less than 180° wherebythere are voids 115 between the ends of the two threads on each part. Onthe part 113 are diametrically opposed barbs 116 in the voids 115.

[0033] When the parts are threadedly connected the barbs 116 areintroduced to the voids 115 on the part 112 before relatively rotatingthe two parts. During rotation the part 112 which is of a plasticsmaterial resiliently deforms as the barbs 116 override the portions 114of the threads on the part 112 before the barbs latch behind the ends ofthe threads on the part 112 to lock the parts 112 and 113 againstdisconnection. In this manner, the injection needle assembly ispermanently coupled to the barrel and cannot be uncoupled withoutdamaging the coupling connector 110.

[0034] It will be understood that the seal 10 will be present duringfitting of the needle assembly to the barrel, i.e. in the course ofengaging the male part 113 to the female part 112, the male part 113will be passed through the aperture 13 in the seal 10 with consequentexpansion of the aperture 13 to accommodate the male part.

[0035] The height of each thread on the female part increases from oneend to the other which provides the abutment against which the barbs 116latch to facilitate the threading operation and deformation of the part112.

[0036] Whilst the injection needle assembly may be fitted to the barrelin a permanent fashion as described above, the filling needle assemblyis releasably connected to the barrel so that it can be used in fillingthe barrel and then removed and replaced by the injection needleassembly. Fitting of the filling needle assembly may be through acoupling means 110 similar to that illustrated in FIGS. 4 and 5 exceptfor the omission of the locking barbs 116. In other words, the part 112of the barrel will be utilised and the mounting portion of the fillingneedle assembly will have the configuration of part 113 except for theomission of the barbs 116 thereby allowing the filling needle assemblyto fitted to the barrel through the sealing cap 10 and subsequentlydisengaged following filling of the syringe barrel.

[0037] Although in FIGS. 4 and 5, the female part 112 is shown as beingassociated with the barrel and the male part 113 with the needleassembly, the arrangement may be reversed so that the male part isassociated with the barrel and the female part with the injection orfilling needle assembly.

[0038] It will be appreciated that it is not intended to limit theinvention to the above examples only, many variations, such as mightreadily occur to one skilled in the art, being possible, withoutdeparting from the scope thereof.

1. A hypodermic syringe barrel provided with a seal adapted to be fittedover the open end of the barrel thereof, the seal comprising a cap of anon-latex elastomer having a central aperture which is sufficientlysmall as ordinarily to retain liquid therebehind but which can bedeformably expanded to allow passage of a mounting portion of a needlefor engagement with the barrel.
 2. A seal adapted to be fitted over theopen end of the barrel of a hypodermic syringe comprising a cap of anon-latex elastomer having a central aperture which is sufficientlysmall as ordinarily to retain liquid therebehind but which can bedeformably expanded to allow passage of a mounting portion of a needlefor engagement with the barrel.
 3. A syringe barrel as claimed in claim1 in which the cap is of silicone rubber.
 4. A syringe barrel as claimedin claim 1 in which the aperture is circular.
 5. A syringe barrel asclaimed in claim 1 in which the aperture takes the form of a number ofslits extending radially outward from the centre of the cap.
 6. Asyringe barrel as claimed in claim 1 in which the cap comprises acircular disc having a cylindrical skirt extending from its rear face.7. A syringe barrel as claimed in claim 6 in which the internalperiphery of the skirt is provided with axially spaced circumferentialribs adapted to engage with circumferential grooves on the end of thebarrel to hold the cap in position.
 8. A syringe barrel as claimed inclaim l in which the needle forms part of a needle filling assembly. 9.A syringe barrel as claimed in claim 1 in which the needle forms part ofa an injection needle assembly.
 10. A barrel as claimed in claim 1,containing liquid which is retained from spillage by the seal if thebarrel is pointed downwardly.
 11. In combination, a syringe barrel asclaimed in claim 1, a needle filling assembly and an injection needleassembly, said assemblies each having a mounting portion for insertionthrough the seal of the aperture for engagement with the barrel.
 12. Thecombination of claim 11 in which the mounting portion of each assemblyis engageable with the same coupling formation on the barrel, thecoupling formation being accessible through the seal aperture.
 13. Thecombination of claim 12 in which the mounting portion of the fillingneedle assembly is releasably engageable with said formation while themounting portion of the injection needle assembly is non-releasablyengageable with said formation.
 14. The combination of claim 13 in whichthe mounting portions and said formation engage via a threadedconnection.
 15. The combination of claim 13 in which the mountingportions and said formation engage via a bayonet connection.
 16. Thecombination of claim 14 in which the injection needle mounting portionand the barrel are provided one with a male part and the other with afemale part and are coupled together through a threaded connectionbetween said male and a female parts, there being a void in anupstanding portion of the thread on each part and a barb in the void onone of the parts, the arrangement being such that when the parts arethreadedly engaged, resilient deformation of at least one of the partsenables the barb to latch behind an end of a thread at the void in theother of the parts to prevent subsequent disconnection of the parts. 17.The combination of claim 16 in which, on each part, there is a two-startthread, the upstanding portion of each thread having a circumferentialextent of less than 180° whereby there are voids between the ends of thetwo threads on each part and diametrically opposed barbs in the voids onthe male part.
 18. A method of preventing spillage of liquid from theopen end of the barrel of a hypodermic syringe comprising fitting theopen end of the barrel with a seal comprising a cap of a non-latexelastomer having a central aperture which is sufficiently small asordinarily to retain liquid therebehind and fitting a needle assembly tothe barrel by insertion of a mounting portion thereof through theaperture so as to deformably expand the seal to allow passage of saidmounting portion for engagement with the barrel.
 19. A method ofpreparing a hypodermic syringe for use in the administration of aninjection comprising fitting the open end of the barrel of the syringewith a seal comprising a cap of a non-latex elastomer having a centralaperture which is sufficiently small as ordinarily to retain liquidtherebehind, coupling a filling needle assembly to the barrel so that amounting portion of the assembly passes through the central aperture inthe seal, operating the syringe to draw liquid into the barrel throughthe filling needle assembly, removing the latter with accompanyingwithdrawal of its mounting portion through the central aperture withconsequent expansion of the central aperture during such removal andsubsequent relaxation of the central aperture to a size consistent withpreventing spillage from the barrel if the latter is pointed downwardly,and fitting an injection needle assembly having a hub by inserting thehub thereof through the central aperture of the seal with consequentexpansion of the central aperture during such insertion.
 20. A method asclaimed in claim 19 in which both needle assemblies are engageable withthe same formation on the barrel, the filling needle assembly beingreleasably engageable with said formation and the the injection needleassembly being non-releasably engageable with the barrel.
 21. A threadedconnection between a male and a female part, there being a void in anupstanding portion of the thread on each part and a barb in the void onone of the parts, the arrangement being such that when the parts arethreadedly engaged, resilient deformation of at least one of the partsenables the barb to latch behind an end of a thread at the void in theother of the parts to prevent subsequent disconnection of the parts. 22.A connection as claimed in claim 21 in which, on each part, there is atwo-start thread, the upstanding portion of each thread having acircumferential extent of less than 180° whereby there are voids betweenthe ends of the two threads on each part and diametrically opposed barbsin the voids on the male part.
 23. A connection as claimed in claim 22in which the height of each thread on the female part may increase fromone end to the other which provides the abutment against which a barblatches.